Reserve power units (RPU) are operative to move a process control component (e.g., a valve) to a shutdown position during a safety shutdown or other power loss situation. When power from a power source is lost (i.e., due to a power outage) the RPU provides power and a control signal to the process control component to cause the process control component to move to a predetermined shutdown position. The RPU stores a sufficient amount of energy such that the process control component can be fully stroked. That is, if the predetermined shutdown position of the process control component is closed, the process control component can be moved from a fully open position to a fully closed position, or other predetermined position, using the energy stored in the RPU. In some examples, the RPU stores a surplus of energy as a precautionary measure.